Trainer cups that comprise a container for liquid and a lid including a mouthpiece, usually in the form of a spout, are well known for use at an intermediate stage in a child's development as the child moves from drinking from a feeding bottle or the breast to drinking from a conventional cup or glass.
However, at that stage, the child will not have learned that if cups are knocked over or shaken, the liquid inside will be spilt. Accordingly, there is a need for the development of trainer cups which are adapted not to spill their contents when shaken or upturned.
United Kingdom Patent Specification GB-A-2 266 045 describes such a cup in which a one-way valve is provided within the spout of the lid of a trainer cup. The valve is formed by a slit formed in an externally convex portion of a sheet of flexible material such as latex or silicone rubber. The valve opens in response to suction on the spout by the child, thereby allowing egress of fluid from the cup. The convexity of the valve provides the one-way characteristic of the valve. A second one-way valve is provided to allow ingress of air into the cup to prevent the build-up of a vacuum.
However, at some stage in a child's development, it will need to learn the skills involved in drinking from the rim of an ordinary cup as opposed to the intermediate type of vessel having a spout. Typically, this is done by wholly removing the lid from the trainer cup to prevent use of the spout. However, in doing so, the spill-resistance advantages are completely lost. The object of the present invention is to provide an improved drinking vessel which can be used as a trainer cup without employing a spout.
As well as being used by children, non-spill and shock resistant drinking vessels can be found useful by a range of other users. For example, the elderly, infirm, the disabled, and those returning from injury would also require such a drinking vessel, as there is an increased chance that the drinking vessel will be dropped on the floor or knocked over. A runner would also require a shock resistant drinking vessel, which would need to be designed to withstand shocks of a different nature to those of other end users. For example, the shock to a drinking vessel when it is dropped affects the fluids dynamics inside the vessel differently than if the vessel is subjected to repeated movements when being held by a runner. As such, a drinking vessel may be required to exhibit different and/or additional shock resistance characteristics depending on the nature of the end use of the drinking vessel.
United Kingdom patent specification no. GB-B-2 401 857 relates to an alternative cup that comprises a cylindrical container and a lid, the lid having a cylindrical outer element that provides a sealing surface, an annular seal and an inner element that serves to trap the seal between an inner surface of the outer element and an outer surface of the inner element. The annular seal and the sealing surface therefore form an annular valve. In use, a user sucks from the rim of the lid, causing a portion of the annular seal of the valve to rise from the sealing surface, thereby allowing liquid contained within the container to flow through the lid to the mouth of the user trying to drink from the cup via the opened portion of the valve. However, the alternative cup of this type employing the annular valve in the lid does not provide an optimum seal to prevent egress of liquid from the container, particularly when the cup is exposed to so-called “shock” movements, for example when the cup is suddenly shaken. Furthermore, it is also desirable to reduce the number of piece parts used to make the cup.